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Author:
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ISBN:
Category :
Languages : en
Pages : 27
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Book Description
Humans perceive linear acceleration and tilt by the otoliths as a result of shear forces on the maculae. A paradigm was set up to study the influence of forces from different directions on the otoliths, on eye movements and tilt perception. On the Coriolis Acceleration Platform of the Naval Aerospace Medical Research Laboratory (NAMRL), five adult male subjects were oscillated in the lateral direction (Y-axis, subject either sitting 'upright' or 'supine') and in the longitudinal direction (Z-axis, subject 'supine' or on his right side). A fifth condition, in which the subject was oriented 'upright' facing the direction of oscillation (X-axis), served as a control condition. In separate sessions, the same subjects were also rotated in these five orientations. Data were obtained by measuring ocular torsion with video-oculography, and the direction of the subjective vertical was recorded by means of a joystick. The sinusoidal oscillations were at 0.22, 0.3, 0.4, and 0.5 Hz, with maximum amplitude of 0.5 g. Rotations were at 17 feet from center at 57 deg/S, which resulted in a centripetal force of 0.5 G on the head. Ocular torsion appeared in all four main conditions (acceleration in Y and Z), but with a significant difference in amplitude. No torsion was found in the control condition (acceleration in X), as was expected. The subjects experienced tilt under centrifugation, and indicated a so-called 'hilltop illusion' during oscillation. The experience of tilt and ocular torsion were most prominent at the lower oscillation frequencies.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 27
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Book Description
Humans perceive linear acceleration and tilt by the otoliths as a result of shear forces on the maculae. A paradigm was set up to study the influence of forces from different directions on the otoliths, on eye movements and tilt perception. On the Coriolis Acceleration Platform of the Naval Aerospace Medical Research Laboratory (NAMRL), five adult male subjects were oscillated in the lateral direction (Y-axis, subject either sitting 'upright' or 'supine') and in the longitudinal direction (Z-axis, subject 'supine' or on his right side). A fifth condition, in which the subject was oriented 'upright' facing the direction of oscillation (X-axis), served as a control condition. In separate sessions, the same subjects were also rotated in these five orientations. Data were obtained by measuring ocular torsion with video-oculography, and the direction of the subjective vertical was recorded by means of a joystick. The sinusoidal oscillations were at 0.22, 0.3, 0.4, and 0.5 Hz, with maximum amplitude of 0.5 g. Rotations were at 17 feet from center at 57 deg/S, which resulted in a centripetal force of 0.5 G on the head. Ocular torsion appeared in all four main conditions (acceleration in Y and Z), but with a significant difference in amplitude. No torsion was found in the control condition (acceleration in X), as was expected. The subjects experienced tilt under centrifugation, and indicated a so-called 'hilltop illusion' during oscillation. The experience of tilt and ocular torsion were most prominent at the lower oscillation frequencies.
Author: Fred H. Previc
Publisher: AIAA
ISBN: 9781600864513
Category : Flight
Languages : en
Pages : 604
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Book Description
Author: Patrice Ba Huy Tran
Publisher: Karger Medical and Scientific Publishers
ISBN: 3805571305
Category : Medical
Languages : en
Pages : 139
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Book Description
Annotation Topics presented were: Ultrastructural features of the two maculae with special emphasis on the neuromediators involved in vestibular signal processing; Review of the physiology of the otolith organs and some fascinating and unexpected roles of these structures in current clinical symptoms; Principal otolith-related syndromes drawing on clinical experience; Development of thoughts on the role of otoliths in movement perception; Clinical and instrumental investigation of otolith function and a critical appraisal for the tests used in vestibulometric practice with emphasis on the experience in eccentric rotatory testing; Use of the subjective visual vertical test, off-vertical axis rotation and click-evoked myogenic potentials as tools for functional investigations of the otolith organs. This volume provides an exhaustive view of the field in vestibulology, not only for neurophysiologists, otologists, neurologists, and kinesitherapists who are specialized in vestibular rehabilitation, but also for geriatrists and specialists in space medicine.
Author: Bernard Cohen
Publisher:
ISBN:
Category : Ear
Languages : en
Pages : 488
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Book Description
This volume summarizes knowledge of static and dynamic processing of ototlith activity in the labyrinth and provides information about otolith processing through the vestibular nuclei and vestibulo-cerebellum. It also addresses how otolith information is processed in the cortex.
Author: Arnauld E. Nicogossian
Publisher: Springer
ISBN: 1493966529
Category : Medical
Languages : en
Pages : 509
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Book Description
As space medicine evolved from the late 1950s onward, the need arose for a ready reference for students and practitioners on the basic concepts of this new specialty. Through three editions edited by leaders in the development of space medicine, this classic text has met the need. This fourth edition of Space Physiology and Medicine provides succinct, evidence-based summaries of the current knowledge base in space medicine and serves as a source of information on the space environment, responses, and practices. Additionally, there is extensive online material available for each chapter, featuring overviews and self-study questions.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Humans perceive tilt by the otoliths as a result of shear forces on the maculae. The current study was designed to investigate the influence of forces from different directions on eye movements and tilt perception. The study was composed of experiments in a human centrifuge. In the first experiment, ocular torsion and experienced tilt due to centrifugal stimulation were assessed, with a maximum of 1.5 G acceleration along the X-, Y- and Z-axes. In the second experiment, the subjects' estimation of tilt was recorded during +1.0 G and -1.0 G centrifugal stimulation along the three axes of the body, with and without visual reference. Results of an earlier study suggested that the utriculus generates conjugate torsional eye movements, and the sacculus generates disjunctive torsional eye movements. This hypothesis found support in the present investigation when the behavior of the two eyes was determined simultaneously. A persistent underestimation of the subjects' tilt perception was registered during stimulation with centrifugal forces less than or equal 1.0 G. This underestimation of tilt appeared least during stimulation along the longitudinal axis (Z, gain: 0.87), and was more prominent during stimulation along the X- and Y-axes (gain: 0.56 and 0.60, respectively). The underestimation occurred even though a calibration procedure was used to control for the possible inadequacy of subjects to adjust intended angles by joy-stick indication. This procedure would exclude such a sensorimotor factor as a cause for the underestimation.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722726355
Category :
Languages : en
Pages : 24
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Book Description
We studied the three-dimensional vestibulo-ocular reflex (VOR) of rhesus monkeys before and after the COSMOS Biosatellite 2229 Mission of 1992-1993. This included tests of ocular counter-rolling (OCR), the gain of the vestibulo-ocular reflex (VOR), and spatial orientation of velocity storage. A four-axis vestibular and oculomotor stimulator was transported to the Institute of Biomedical Problems in Moscow for the pre- and postflight ground-based testing. Twelve normal juvenile male rhesus monkey were implanted surgically with eye coils and tested 60-90 days before spaceflight. Two monkey (7906 and 6151), selected from the twelve as flight animals, flew from 12/29/92 to 1/10/93. Upon recovery, they were tested for 11 days postflight along with three control animals. Compensatory ocular torsion was produced in two ways: (1) Lateral head tilts evoked OCR through otolith-ocular reflexes. OCR was also measured dynamically during off-vertical axis rotation (OVAR). (2) Rotation about a naso-occipital axis that was either vertical of horizontal elicited torsional nystagmus through semicircular canal-ocular reflexes (roll VOR). OCR from the otoliths was substantially reduced (70 percent) for 11 days after reentry on both modes of testing. The gain of the roll VOR was also decreased, but less than OCR. These data demonstrate that there was a long-lasting depression of torsional or roll eye movements after adaptation to microgravity in these monkeys, especially those movements produced by the otolith organs. Dai, Mingjia and Mcgarvie, Leigh and Kozlovskaya, Inessa and Sirota, Mischa and Raphan, Theodore and Cohen, Bernard Unspecified Center NAG2-573; NAG2-703...
Author: Andrew H. Clarke
Publisher: Springer
ISBN: 331959933X
Category : Medical
Languages : en
Pages : 85
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Book Description
This monograph describes the findings of spaceflight research related to spatial orientation, sensorimotor coordination and mental function. Exposed to the microgravity conditions of spaceflight, the human experiences a variety of physiological and psychological problems, which are presented here. Recent findings of sensory motor research in space are depicted and their benefits for life on earth discussed. The examination of the vestibulo-oculomotor system for example has led to the development of innovative devices for the measurement of three-dimensional eye and head movements. These devices are currently employed in Earthbound applications such as eye laser surgery. The book is written for students and researchers in neurosciences, biomedical engineering, for neurologists and psychologists as well as for persons wanting to know more about biomedical research in space and its application on earth.
Author: R. John Leigh
Publisher: Oxford University Press
ISBN: 0190451017
Category : Medical
Languages : en
Pages : 240
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Book Description
This volume brings together work from leading researchers in the fields of developmental disorders of binocular vision, strabismus, and both infantile and acquired forms of nystagmus. It contains four sections. The first section, Basic Concepts of Stable Vision and Gaze, deals with psychophysical aspects of infantile forms of nystagmus and the relative contributions of extraocular proprioception and efference (corollary discharge). It also contains an accessible review of current notions of spatial and temporal visual functions and spatial constancy in infantile nystagmus syndrome and latent nystagmus. The second section, New Models and Techniques for Studying Gaze Stability, reviews animal and development models for strabismus, amblyopia, and nystagmus. It also contains novel optical methods for managing the visual consequences of nystagmus and a study of the potential ill effects of video displays on children's response to near viewing. The third section, New Therapies for Congenital Nystagmus, presents basic genetic studies and clinical trials of drug and surgical treatment of those patients with infantile forms of nystagmus. The final section,General Aspects of Normal and Abnormal Gaze Control, pulls together a range of contributions dealing with normal gaze control, infantile nystagmus, and acquired disorders of eye movements, including new treatment measures. This book will be a valuable resource for all scientists and practitioners interested in developmental disorders of vision.
Author: Mawuli Israel Tse
Publisher:
ISBN:
Category :
Languages : en
Pages : 166
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Book Description
